DESCRIPTION (provided by investigator): We propose to study children who sustain moderate to severe traumatic brain injury (TBI) to address 3 Aims: (1) changes in cognitive control as reflected by working memory, different forms of inhibition, and allocation of attentional resources; (2) changes m response to motivational manipulations and decision making; (3) changes in social cognitive skills, including processing of emotional expression and intentionality. Changes in cognitive control, motivation, and social cognition will be analyzed in relation to age at injury, TBI severity, and brain imaging using magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), diffusion tensor imaging (DTI), and functional MRI (fMRI). We will also study the impact of changes in cognitive control, motivation, and social cognition on executive functioning in everyday activities, adaptive skills, psychosocial function, and psychiatric status, taking into account moderator variables of family environment and family burden. Eighty-five children age 6-16 years who sustain moderate to severe TBI, and a comparison group of 85 children who sustain orthopedic injury (OI), will be recruited during initial hospitalization and studied within 1 month and at 3, 12, 18, and 24 months post injury. Cognitive control measures include Sternberg Item Recognition, Directed Forgetting, and Flanker tasks, which compare different processes within the same task using the same metrics. Allocation of attentional resources will be measured by tasks that switch conditions and by a dual task. Motivation tasks assess children's ability to selectively learn material reflecting reward contingencies and their response to intrinsic or extrinsic reward. Social cognition will be evaluated by processing emotional expression and intentionality, with measurement of cognitive mediators. MRS will evaluate changes in regional metabolite concentrations, DTI will quantitate change in the integrity of axonal tracts in various Iobular regions of TBI and OI patients, and the pattern of brain activation while performing a working memory task will be studied using fMRI. We will compute focal lesion volumes from MRI. Outcome domains are assessed by standardized measures of academic achievement, executive functioning in everyday activities, and psychosocial function. Structured interviews will evaluate pre- and postinjury psychiatric status. Specific aims will be addressed primarily by general linear mixed models when data are relatively symmetric, or by general nonlinear mixed models when they are not. Some hypotheses will be tested using latent growth curve modeling. [unreadable] [unreadable]